Simon Bridges has revealed he dropped out of the race for National party leader because he didn't have the numbers.

Bridges, who has previously held the top job, made an eleventh-hour decision to back Christopher Luxon before Tuesday's caucus meeting.

He's since picked up the finance portfolio under Luxon's new reign. 

Bridges told Heather du Plessis-Allan the decision to step away from his leadership ambitions wasn't painful.

“It was close, but not close enough. I mean, I don't mind being open about that. I think it also helps that I saw in Chris Luxon, someone I know well, someone I could believe in.”

Meanwhile, Bridges says his son is recovering in Starship Hospital after a serious playground accident.

He missed a press conference he was meant to be attending yesterday with Luxon as he was in the ambulance with his son Harry.

Bridges says Harry tore his liver and has suffered some internal bleeding, but he says Harry will pull through.

“He’s getting there. It’s a slow process, we’ve got to monitor him, but yeah, I think we can feel pretty confident that he’s gonna get there and he’s gonna be OK, which is great.”

LISTEN ABOVE